Step stool



FIG. 1 is a perspective view of a step stool showing my new design;

FIG. 2 is another perspective view thereof;

FIG. 3 is a front elevational view thereof;

FIG. 4 is a rear elevational view thereof;

FIG. 5 is a left side elevational view thereof;

FIG. 6 is a right side elevational view thereof;

FIG. 7 is a top plan view thereof;

FIG. 8 is a bottom plan view thereof;

FIG. 9 is an exploded perspective view of the step stool;

FIG. 10 is an enlarged view of portion 10 shown in FIG. 1 ;

FIG. 11 is an enlarged view of portion 11 shown in FIG. 1 ; and,

FIG. 12 is an enlarged view of portion 12 shown in FIG. 9 .

The dash-dash broken lines in the drawings depict portions of the step stool that form no part of the claimed design. The dot-dash broken lines represent boundaries of the enlarged portions and form no part of the claimed design. 

CLAIM The ornamental design for a step stool, as shown and described. 